CVE-2021-47474

Kernel memory corruption via oversized USB bulk transfer

Published May 22, 2024 · Updated May 11, 2026

Buffer overflow in the Linux vmk80xx Comedi driver allows physically proximate attackers to corrupt kernel memory via a malicious USB device. vmk80xx_do_bulk_msg uses the transmit endpoint's maximum packet size as the receive-transfer length, which can overrun a smaller usb_rx_buf allocation. The device must be attached and trigger a bulk transfer; the resulting kernel-memory corruption can crash the host.

CVSS severity7.8
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in the Linux vmk80xx Comedi driver allows physically proximate attackers to corrupt kernel memory via a malicious USB device. vmk80xx_do_bulk_msg uses the transmit endpoint's maximum packet size as the receive-transfer length, which can overrun a smaller usb_rx_buf allocation. The device must be attached and trigger a bulk transfer; the resulting kernel-memory corruption can crash the host.

The record

CVE
CVE-2021-47474
Published
May 22, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787, T1200
Attack vector
physical
Privileges
Unavailable

Timeline

How it unfolded

  1. May 22, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.31
  2. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <063f576c43d589a4c153554b681d32b3f8317c7b
  3. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <0866dcaa828c21bc2f94dac00e086078f11b5772
  4. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <1ae4715121a57bc6fa29fd992127b01907f2f993
  5. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <47b4636ebdbeba2044b3db937c4d2b6a4fe3d0f2
  6. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <78cdfd62bd54af615fba9e3ca1ba35de39d3871d
  7. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <7b0e356189327287d0eb98ec081bd6dd97068cd3
  8. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <7cfb35db607760698d299fd1cf7402dfa8f09973
  9. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <b7fd7f3387f070215e6be341e68eb5c087eeecc0
  10. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <e0e6a63fd97ad95fe05dfd77268a1952551e11a7

What conditions does exploitation require?

Attack vectorphysical
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.31; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <063f576c43d589a4c153554b681d32b3f8317c7b; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <0866dcaa828c21bc2f94dac00e086078f11b5772; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <1ae4715121a57bc6fa29fd992127b01907f2f993; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <47b4636ebdbeba2044b3db937c4d2b6a4fe3d0f2; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <78cdfd62bd54af615fba9e3ca1ba35de39d3871d; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <7b0e356189327287d0eb98ec081bd6dd97068cd3; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <7cfb35db607760698d299fd1cf7402dfa8f09973; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <b7fd7f3387f070215e6be341e68eb5c087eeecc0; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <e0e6a63fd97ad95fe05dfd77268a1952551e11a7

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1200Hardware Additions

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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